Corrosion destroys heat output at Millennium Centre

Samples of circulating water showing progress of system cleaning at the Millennium Centre

Corrosion is the most common cause of major problems in heating systems; something that the three-storey Millennium Centre building in St Helens knows only too well. Over the course of just a few years, heat output from the facility’s commercial heating system decreased to almost nothing, despite rising thermostats. Upon inspection, boiler manufacturer-endorsed water treatment specialist, Sentinel Commercial, along with Richard Cumber, a leading exponent of water treatment, found that the heating system had severely corroded and was almost entirely blocked with thick, iron oxide corrosion deposits. The specialists then implemented a programme of best practice system cleaning and protection. For the Millennium Centre (a registered charity), the solution delivered a valuable return on its investment, not only fully restoring heat to the building, but providing significant savings on maintenance and energy costs.

The Millennium Centre in St Helens

The Millennium Centre is a purpose-built multi resource facility that was built in 2001. It provides space to more than 70 charities and statutory organisations, including an NHS Walk-in Centre, Citizens Advice Bureau, pharmacy and Visual Impairment Resource Centre. Facilities at the Millennium Centre also include multiple free-of-charge rooms for meetings, training, conferences, counselling and therapy. To heat the building, a low temperature hot water system comprising two steel commercial boilers was installed, with radiant panel radiators and air handling units to supply heat to rooms and offices.

Liz Elliott, Assistant to the Executive Chairman at the Millennium Centre, said: “From 2013 we started to experience serious problems with the heating system. Typically, it would be in some parts of the building and off in others. The issues gradually worsened through to 2015, when at times we were getting no heat output whatsoever. It was then that we decided action was absolutely necessary.”

Between 2013 and 2015, tenant and visitor comments turned to complaints as the heating system repeatedly failed. In late 2015, the building’s maintenance company, which had unsuccessfully tried to clean and flush the system, turned to water treatment manufacturer, Sentinel Commercial, for a solution.

Chris Shelton, Sales Director of Sentinel Commercial, and Richard Cumber led the project. Initial inspection of the building’s heating system uncovered severe and extensive corrosion, as Mr. Cumber explained:

“We opened the strainer on the air handling ductwork and what looked like crude oil emerged. It was a truly severe level of corrosion, one of the worst that I had seen despite working in water treatment for several decades.”

Analysis confirmed that the thick black substance was mainly iron oxide, a product of corrosion. A sample of system circulating water was also analysed for suspended solids, conductivity, molybdate, and total and dissolved iron.

Further inspection revealed that corrosion had accumulated inside most of the building’s radiant panel radiators, preventing the circulation of water. The build-up of corrosion debris can affect radiant panel radiators particularly gravely due to their horizontal positioning, which means that heavy iron oxide particles can accumulate quickly inside the radiators’ flat, internal copper tubing.

Corrosion debris was also found to be entirely blocking the flexible heating pipes that connect the radiators to the main heating system. With an internal diameter of 10mm, these had clogged rapidly. Consequently, the flow of circulating water throughout much of the vast and complex heating system was negligible to non-existent.

The boiler plant room at the Millennium Centre

The chief cause of corrosion within the Millennium Centre’s heating system was caused by a combination of poor water treatment and excessive oxygen ingress. Corrosion can lead to range of serious issues from complete boiler failure (sometimes within months of commissioning) and premature repairs and parts replacements, to increased energy consumption and – as the Millennium Centre can testify – poor heat output.

“We reviewed documentation for the system but there was nothing to indicate any kind of pre-commission cleaning or inhibitor treatment. It’s reasonable to assume, especially given the state of the system, that it had not been treated at all. This particular system has a real mix of metals, so the potential for corrosion in the absence of proper water treatment is great,” explained Mr. Shelton.

The solution arrived in the form of best practice water treatment using Sentinel Commercial’s boiler-manufacturer endorsed chemicals. Best practice water treatment comprises: cleaning to remove debris and restore system efficiency; adding inhibitor to prevent further corrosion and limescale; and regular maintenance of system water.

Sentinel 8500 Cleaner was used as part of a two-stage cleaning process. Firstly, 3% of system volume cleaner was introduced to the system where it was left for 24 hours. During this time, all of the system’s flexible hoses were disconnected so that resident debris could be pushed out using a metal rod. The system was then flushed before a further 3% of system volume cleaner was added and left for another 24 hours – again followed by flushing.

The conductivity of the system water was measured to ensure it was within 10% of mains water conductivity, before Sentinel X100 Inhibitor was added. In fact, an increased level of X100 Inhibitor was introduced because this advanced product continues to clean a system by taking iron oxide into solution. As a result, X100 Inhibitor’s long-term corrosion control properties are excellent.

Within two weeks of system cleaning and inhibitor introduction, tenants said that the heat was coming through. A week later people were complaining that it was too hot, principally because many of the building’s thermostatic valves had previously been set at maximum to try and combat the dysfunctional system. Sentinel Commercial and Mr. Cumber duly recommissioned the heating system’s control to better regulate the heat. The building could then be heated properly and, two years on, the system is still working great.

“The centre opens from 07:00 to 22:00, which means we have staff on site from 06:00 to 23:00. With this in mind, the heating system works long hours, particularly in the colder months. However, we’ve had no complaints whatsoever about lack of heat since the remedial works took place,” said Ms Elliott.

Beyond rectifying the previous heating issues, the work carried out by Sentinel Commercial and Mr. Cumber has also led to financial savings.

“The biggest difference has obviously been our maintenance costs. We were continuously calling our previous heating contractor, whereas now the system looks after itself with the occasional monitoring check,” said Ms. Elliott.

After completing the works, it was agreed that Sentinel Commercial and Richard Cumber (now Managing Director of Intuit Solutions Ltd) would monitor the iron levels in the heating system due to its previously perilous state.

“I’ve seen for myself some of the samples that have been collected since the system has been cleaned and treated, and the difference in corrosion content is astonishing compared with previous levels, so we know the inhibitor is doing a terrific job. We have also noticed that our energy bills are slightly less than before. This saving, together with the large reduction in maintenance costs, means the project will pay for itself.” Ms. Elliott concluded.

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